Blender output file size versus Zoom recording file size
I've tried to import a zoom-recording (downloaded from the internet; 53MB) in Blender 2.91 and the rendered output file from Blender was only slightly larger (55MB). Maybe you can try version 2.91?
However, if your only need is to silence some part of your video, then you can easily/fast do it with ffmpeg. The command is as follows (all on one line):
ffmpeg -i zoom_0.mp4 -af &quot;volume=enable='between(t,0,10)':volume=0, volume=enable='between(t,20,30)':volume=0&quot; zoom_silenced.mp4

The input-file is zoom_0.mp4. The output-file is zoom_silenced.mp4. Two periods are slienced: from second 0 (begin) to second 10 and again from second 20 until second 30.
You can find more information at: https://stackoverflow.com/questions/29215197/mute-specified-sections-of-an-audio-file-using-ffmpeg. There are also lots of YouTube-tutorials on how to install ffmpeg.